Metal roof structures typically comprise a series of parallel rafter beams extending across the building in one direction and purlin beams parallel to each other mounted on top of the rafters extending in a direction normal to the rafters. Insulation is material in long sheets is placed in the area between purlins. The sheets of insulation material can be laid along the length of the purlins or across the purlins in a direction normal to the purlins. If desired, the roof structure can have a first layer of insulation material which is laid along the length of the purlins, and a second layer of insulation material which is laid laterally across the purlins on top of the first layer on insulation. Hard roofing material such as metal decking is then attached on top of the purlins over the insulation material. Because the hard roofing material comes in long sheets and the roofs generally have two sloped sections, it is customary to construct the roof along the length of the structure from one end to the other. The workers stand on the previously laid section of roof to construct the next section.
The insulation material is supported between the purlins beneath the hard roofing material. Various methods of supporting the insulation material have been used. Mounting straps or wire mesh which are attached to or draped over the purlins forming a lattice have been used. This is referred to as banding. A sheet, typically made of vinyl and acting as a vapor barrier, is then rolled onto the lattice, and insulation material is placed between adjacent purlins and over the sheet. If the installation of the lattice is done from underneath the roof structure, scaffolding or lifting equipment is typically required for installation. Since the lattice encompasses the entire roof, installation is costly and time consuming. Once the hard roofing material is mounted on the purlins, the sheet can support the insulation material and the lattice no longer serves any useful purpose.
Some systems dispense with the lattice and use the sheet itself to support the insulation material. The support sheet is dispensed from a roll and draped from adjacent purlins. Insulation material is then placed on top of the support sheet. A carriage has been used to aid in the dispensing of the support sheet, such as that disclosed in U.S. Pat. No. 4,967,535 to Alderman. The carriage is positioned on top of the purlins and travels the length of the purlins during the roof construction. A roll of the support sheet material is mounted on the carriage and the support sheet is dispensed from the roll and placed on top of the purlins. As the carriage travels the length of the purlins, the support sheet is draped across the purlins.
The carriage can be any length up to the width of the roof itself. For example, the carriage can be comprised of a plurality of carriage sections which are joined together so that they span the entire width of the roof. Each carriage section has a roll of support sheet dispensing the support sheet across two adjacent purlins. The carriage is then propelled along the length of the purlins so that the carriage sections move in unison.
In the past, the carriage was manually pushed across the roof along the length of the purlins by means of push rods. The workers standing on a completed section of the roof structure would manually push the carriage to the desired position. Another method of advancing the carriage was by pulling the carriage across the roof by means of a relatively long cable and large winch fastened to the carriage. The cable was typically 200 feet long and had a conventional hook attached at the end of the cable. The cable was reeled out from the spool of the winch and then hooked to a flange of a rafter beam. If the roof structure was longer than 200 feet, the cable was attached to the farthest rafter beam which the cable was able to reach. The winch was then manually operated to take up the cable about the spool of the winch so as to advance the carriage. It was preferred that the cable be as long as possible, so that the cable did not have to be re-attached to a different rafter beam often. Because the winch is attached to the carriage and moves over and across the rafter beams, the cable is laid across the tops of all the rafter beams between the carriage and the end of the roof structure. However, it can be difficult and time consuming to unroll the cable and pull the end of the cable across the rafter beams 200 feet away from the carriage. It is also difficult to initially attach the hook at the end of the roof structure since this requires a worker to climb to the top of the end of the roof structure. Since the cable is relatively long, the cable is relatively heavy and awkward to handle. Also, the size of the winch is relatively large and heavy to accommodate the length of the cable required to span across the roof structure.
It would be desirable to have an apparatus and method for moving the carriage along the length of the purlins which is relatively simple, fast, and safe to perform.